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Page 8
Library Features
Auto Unload Mode
SCSI ID Modification
LUN 1 Command Forwarding
The SCSI Read Block Limits command returns the minimum and maximum block
sizes that the Viper drive can support. The Block Limits data is not modified to reflect
the current mode of writing—fixed or variable. The Block Limits returned data is not
modified to reflect the current block size for the next fixed-mode Write. The Mode
Sense command is used for that purpose.
The Viper drive has an Auto Unload Mode that may be accessed via a Mode
command to Mode Page 21h. Auto Unload mode allows the drive to be configured
for Library systems or as a standalone drive. Auto Unload mode allows the drive to
control how the tape is unloaded in automated environments. Auto Unload modes
provide three options for tape unloading:
•
Do Nothing – Stay at BOT or Stay SEATED.
•
Unthread Only
•
Unthread and unload
The list below provides examples of automation situations in which the ejection
process may be controlled using the Auto Unload mode. These examples include not
only normal power-on situations, but situations involving cleaning tapes, incompatible
tapes and firmware tapes.
•
Powering on or power cycling while the tape is inside the drive
•
Cleaning tape has finished the cleaning cycle
•
Unsupported data tape has been loaded
•
Unsupported cleaning tape has been loaded
•
Microcode download from a firmware tape
•
Microcode download via the SCSI Write Buffer command while a tape is loaded
Tape libraries require that the SCSI ID of an installed tape drive can be changed
without opening the library enclosure and changing address jumpers. To change the
SCSI ID of the Viper drive, issue a Mode Select command to Mode Page 22h to
change the Next Selection ID field to the desired SCSI ID. After you reset or cycle
the power to the drive, it will begin responding to the new SCSI ID. The new ID will
persist through additional resets and power cycles.
If the address jumpers are changed and the drive's power is cycled, the drive will
respond to the new address on the jumpers. The value in the Next Selection ID field
will be that on the jumpers, even though the field may have been changed
immediately before the power cycle.
A tape library or autoloader containing a Viper can receive its SCSI commands via
the Viper. This function is called "Command Forwarding" and is enabled via the
"CmdFwd" field in the Interface Control mode page (22h). When enabled, commands
received via the SCSI bus and addressed to LUN 1 are immediately transmitted to
LTO SCSI Interface Manual
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